The McLeod pitch method is a real-time algorithm for detecting the fundamental frequency of a musical sound. It was presented by Philip McLeod and Geoff Wyvill in their paper A Smarter Way to Find Pitch. The method builds on autocorrelation, comparing a sound wave against delayed copies of itself, but improves it with a normalized square difference function that reduces the octave errors and instability that plague simpler approaches. The result is a pitch estimate that stays accurate across a wide range of instruments and voices while remaining fast enough to update many times per second. Those qualities make it a strong choice for browser-based tuners, where the signal arrives continuously from the microphone and the display must respond without noticeable lag. Because it reports a clean fundamental even when the sound is rich in overtones, it handles guitar, bass and voice well. FretMind's chromatic tuner uses the McLeod pitch method to convert your microphone input into a steady, precise pitch reading.